<template>
  <div class="goods-image">
    <!-- 大图容器 -->
    <div v-show="isShow" class="large" :style="[{backgroundImage:`url(${images[currIndex]})`},bgPosition]"></div>

    <!-- 左侧图片容器 -->
    <div class="middle" ref="target">
      <img :src="images[currIndex]" alt="">
      <!-- 遮罩层 -->
      <div v-show="isShow" class="layer" :style="position"></div>
    </div>

    <!-- 右侧小图 -->
    <ul class="small">
      <li v-for="(img,i) in images" :key="img" :class="{active:i===currIndex}">
        <img @mouseenter="currIndex=i" :src="img" alt="">
      </li>
    </ul>

  </div>
</template>
<script>
import { ref, watch, reactive } from 'vue'
import { useMouseInElement } from '@vueuse/core'

const usePreviewImage = () => {
  // 显示与隐藏
  const isShow = ref(false)

  // 监测目标
  const target = ref(null)

  // 遮罩层位置
  const position = reactive({
    top: 0,
    left: 0
  })

  // 右侧预览大图位置
  const bgPosition = reactive({ backgroundPositionX: 0, backgroundPositionY: 0 })

  // @vueuse/core方法监测鼠标在Dom上移动
  const { elementX, elementY, isOutside } = useMouseInElement(target)

  watch([elementX, elementY, isOutside], () => {
    // 控制显示隐藏
    isShow.value = !isOutside.value

    // 判断是否没进入监视区
    if (isOutside.value) return

    // 控制遮罩层X轴移动范围
    if (elementX.value < 100) {
      position.left = 0
    } else if (elementX.value > 300) {
      position.left = 200
    } else {
      position.left = elementX.value - 100
    }

    // 控制遮罩层Y轴移动范围
    if (elementY.value < 100) {
      position.top = 0
    } else if (elementY.value > 300) {
      position.top = 200
    } else {
      position.top = elementY.value - 100
    }

    // 根据 遮罩层位置计算出预览大图位置
    bgPosition.backgroundPositionX = -position.left * 2 + 'px'
    bgPosition.backgroundPositionY = -position.top * 2 + 'px'

    // 加单位
    position.top = position.top + 'px'
    position.left = position.left + 'px'
  })
  return { position, target, bgPosition, isShow }
}

export default {
  name: 'GoodsImage',
  props: {
    images: {
      type: Array,
      default: () => []
    }
  },
  setup (props) {
    const currIndex = ref(0)
    const { position, target, bgPosition, isShow } = usePreviewImage()
    return { currIndex, target, position, bgPosition, isShow }
  }
}
</script>

<style scoped lang="less">
.goods-image {
  width: 480px;
  height: 400px;
  position: relative;
  display: flex;
  z-index: 500;
  .large {
    position: absolute;
    top: 0;
    left: 412px;
    width: 400px;
    height: 400px;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    background-repeat: no-repeat;
    background-size: 800px 800px;
    background-color: #f8f8f8;
  }
  .middle {
    width: 400px;
    height: 400px;
    background: #f5f5f5;
    position: relative;
   cursor: move;
   .layer {
     width: 200px;
     height: 200px;
     background: rgba(0,0,0,.2);
     left: 0;
     top: 0;
     position: absolute;
   }
  }
  .small {
    width: 80px;
    li {
      width: 68px;
      height: 68px;
      margin-left: 12px;
      margin-bottom: 15px;
      cursor: pointer;
      &:hover,&.active {
        border: 2px solid @xtxColor;
      }
    }
  }
}
</style>
